In a software-defined network (SDN), control decisions for routing traffic through the network can be decoupled from the network's physical infrastructure. For example, in some SDNs, a network controller can instruct network switches to flow traffic along a selected routing path defined by network switches. Other functionality can be achieved through the use of software-defined networking. For example, SDN applications can be installed on or interface with a network controller to meet customer use cases, such as to achieve a desired throughput or other quality of service.